I know a guy who tosses a couple of pucks under there, so he says at least, I would love to see his liner under the steps. Plus his CYA levels are probably high from doing that, he does not use the BBB method either. That is what has kept me from buying those steps, what about coring some 2" holes through the sides here and there? What about piping in a return jet behind them, or a combination of the two, if you were blasting the water in there and it was coming out the holes it would be circulated.